Cleaning and buffing product



Nov. 3, 1970 1-. R. M AVOY CLEANING AND BUFFING PRODUCT Filed Jan. 17,1968 I NVEN TOR. I grownsfifl flvar United States Patent 3,537,121CLEANING AND BUFFING PRODUCT Thomas R. McAvoy, Stillwater, Minn.,assignor to Minuesota Mining and Manufacturing Company, St. Paul, Minn.,a corporation of Delaware Filed Jan. 17, 1968, Ser. No. 698,497 Int. Cl.A471 11/40 US. Cl. 15230.12 5 Claims ABSTRACT OF THE DISCLOSURE A softresilient compressible polishing pad which is superior to lambs wool forbuffing aluminum, paint, wax, plastic, and similar surfaces. The pad isessentially a lofty fibrous nonwoven structure bonded by a soft, toughresin containing a finely divided soft mineral filler.

BACKGROUND OF THE INVENTION The invention relates to pads for cleaning(with compounds), bufling, or restoring surfaces.

For decades lambs wool polishing pads or bonnets have been the standardproduct for use when a painted or waxed surface was to be buffed tobring up its luster. Such pads, which are conformable and soft, haveheretofore been superior to any other product for this purpose.

Lambs wool pads do, however, suffer from several inherent drawbacks.They are expensive and, like most natural products, subject tounpredictable variation. The rough surface of wool fibers and theirtendency to mat under pressure results in seizing or drag, causingoperator fatigue. The presence of even a slight amount of moisture onthe surface being bufied, as is often the case, further emphasizes thisproblem.

The same characteristics also cause lambs wool pads to clog with wax ordirt during use, which in turn aggravates the tendency to seize. Removalof such dirt and Wax is complicated by another characteristic of woolthepresence of a leather face on one side which prevents the ready flow ofwater or other cleaning solution through the pad. Further, hot watermust not be used, lest the wool shrink, kink and distort.

Still another defect of lambs wool is the tendency of a disc formedtherefrom to leave swirl marks, perhaps as the result of the wool fibersaligning themselves concentric with the axis of rotation of the drivingpad, the local formation of knots, or the collection of dirt spots atthe surface. Such marks are visually unattractive, no matter howsuccessful the bufling operation may be in increasing luster.

As might be expected, many attempts have been made to devise a syntheticreplacement for lambs wool pads, but prior to the present invention suchattempts have not been successful. One obvious substitute for a lambswool pad is a disc cut from carpeting, but it has essentially the sameproblems found in lambs wool.

US. Pat. 2,958,593 discloses and claims a nonwoven lofty open mat formedfrom randomly disposed fibers which are bonded at points where theyintersect and contact each other. An adhesive, such as phenolic resin,is used to bind abrasive grains to the fibers, the resultant productbeing characterized by large voids, through which water and detritusreadily pass. Pads formed from such material are compressible,conformable, easy to clean, and low in drag, but they tend to remove asoft surface and/or leave scratch marks, no matter how fine the abrasiveparticles employed. Even if abrasive grains are omitted, the resinitself leaves scratches in such surfaces, actually removing wax orpowdering the ice surfaces of hard synthetic polymer floor finishes,lacquers and similar material. This patent recommends the use of binderresins having a Knoop hardness of 6 or considerably higher (although itindicates somewhat softer binders can be used with some decrease ineffectiveness). It has been found that resins having a Knoop hardness aslow as 10 cause scratches.

British Pat. 1,006,005 and 1.0l4,297 disclose abrasive articles similarto those in US. Pat. 2,958,593 except that an extremely soft (e.g.,Knoop hardness of 1 or 2) adhesive is used to hold the abrasive grainsto the fibers, the nonwoven abrasive product being adhered to a supportfor additional strength. Again, pads formed from such products tend toscratch and remove soft substrates, no matter how fine the abrasiveparticles. If the abrasive grains are omitted altogether, the problem ofscratching is eliminated, but the tendency of the pad to drag exceedseven that exhibited by lambs wool.

SUMMARY OF THE INVENTION The present invention provides products whichare comparable to lambs wool in ability to impart luster to butfablewaxes and which can be used to clean and restore the surface of hardpolymer coatings without powdering. These products do not scratch orabrade the surface being buffed, do not impart swirl marks to thefinish, and yet exert a drag far lower than that obtained with lambswool pads. The novel buffing products resist loading with detritusremoved from the surface being buifed, and even those materials which doeventually work their way into the pad can be readily washed free. Bothfaces of the pad can also be used, thereby effectively increasing itsusefulness.

The invention comprises a lofty nonwoven mat formed essentially fromtough strong resilient fibers bonded together at points where they crossand contact each other with a binder comprising a soft resin (e.g.,Knoop'hardness of less than 3); to this extent they are similar toproducts disclosed in the aforementioned British patents. In addition tobeing soft, the resin in the binder is flexible, tough, resilient andsomewhat elastomeric, a particularly preferred resin being a flexiblepolyurethane. The binder also contains, based on the total volume ofbinder, from about 10 to about 65% of a finely divided mineral fillerwhich has a Knoop hardness of no more than about 150, and preferablyconsiderably lower. (Crocus, the softest abrasive grain used in coatedabrasive products, has a Knoop hardness of about 600, and calciumcarbonate, whose Knoop hardness is about 135, is a common extender foradhesives used in the manufacture of coated abrasive products; hence itwill be appreciated that the mineral used in this invention trulyfunctions as a filler, not as an abrasive grain.) Suitable fillersinclude calcium carbonate, kaolin, and talc, which has a Knoop hardnessof 12 or less and is presently preferred. The filler desirablyconstitutes about /6 to /2 the volume of binder, the presently preferredvalue being about 6.

Synthetic fibers which are not especially affected by moisture areparticularly preferred for the practice of this invention fibers oforiented polyethylene terephthalate fibers proving especially suitable.If desired, however, fibers which are not themselves satisfactory may beblended in with fibers of the type just described; for example, rayonfibers may be blended in with polyester fibers. Fibers having a diameteron the order of 10-50 microns may be employed, with fibers in the 2040micron range being particularly preferred. In general, the finer thefibers, the less open the pad and the less its tendency to impart swirlmarks but its greater the tendency to drag. (The open structure of US.Pat. 2,958,593 is based on fibers having a diameter of at least about 25microns.)

3 BRIEF DESCRIPTION OF THE DRAWING For convenience in visualizing theproduct of this invention, attention is directed to the accompanyingdrawing, in which the single figure represents a view in perspective ofa polishing pad made in accordance with this invention.

In the drawing, the pad is formed from randomly disposed and interlacedfibers, bonded together at points where they cross and contact eachother with a binder which is made up of a soft, tough resin and softmineral filler, as previously described.

Pads of this type may be driven by a conventional floor surfacingmachine, or attached to a inch electric drill or other rotary drivingbufling tool. It will be recognized, of course, that rectangular padscan be prepared and used on reciprocating, oscillating, or orbitalheads.

Although there is considerable subjectivity involved in evaluating aneffective butfing pad, a number of tests are useful in providing anevaluation of performance and other physical characteristics. Forexample:

Tensile test.-This figure should generally exceed about 15 lbs. perlineal inch in mutually perpendicular directions in the plane of thepad.

60 gloss value-Interim Federal Specification No. P-0040b(GSA-FSS)provides certain standards relating to the preparation and testing ofbuffable waxes containing a high percentage of Carnauba wax. Inaccordance with this test, a 4-inch diameter disc of /8-l110h blackasphalt tile is covered with a brush coat of 16% solid water emulsion ofa butfable wax, allowed to dry for one hour, and adhered to the rigidrotary support of a Schiefer abrasion testing machine. A 4-inch diameterfloor surfacing pad is afiixed to a second rotary support and positionedover the tile disc so that slightly over half of the diameters overlap.The disc and pad are then rotated at 250 rpm. for 200 revolutions underan applied force of 5 lbs. The tile is subjected to a 60 glossmeasurement in accordance with ASTM Test Specification No. 141. Glossvalue should be at least 30.

Abrasive characteristics.A black asphalt 4-inch diameter tile is coatedwith about 25 milligrams of a hard acrylic polymer finish (e.g., StepAhead sold by S. C. Johnson and Son, Inc.), and subjected to theSchiefer test described above. The weight of the coated tile is measuredbefore and after testing, visually checked for any appearance ofpowdered finish. Polymer weight loss should not exceed about 4milligrams, and little or no white powder should be visible.

Drag.--A 17-inch diameter pad is placed under the driving assembly of aconventional electrically powered floor surfacing machine, in the linecircuit of which is connected an ammeter showing a no-load reading of6.8. The amperage is monitored while the pad being tested is moved overa hard polymer floor surface coating, readings being taken both in levelposition and when the pad is heeled to move it from place to place.Desirably the amperage should not increase more than about 1.2 when themachine is heeled. In contrast, for example, a machine faced with alambs wool pad normally draws about 1.3 amperes over no-load when leveland 2.6 amperes over no-load when heeled.

DESCRIPTION OF PRESENTLY PREFERRED EMBODIMENTS Although considerablelatitude is permissible in constructing products in accordance with thisinvention, it is believed that understanding will be facilitated byreferring to the following illustrative but nonlimiting examples. Partsare by weight, unless otherwise indicated.

EXAMPLE 1 A lofty nonwoven Web was formed on a Rando-Webber machine from15 denier (approximately 40-micr0n diameter) l /z-inch crimped orientedpolyethylene terephthalate fibers. The web was approximately 2 inchesthick and weighed approximately 68 grams per 24 square inches of web.

A mineral-filled binder, containing about 30% soft mineral filler byvolume, was prepared by blending and curing the following components:

Parts by weight Ethylene glycol monoethylether acetate 400 Liquidpolyester resin, having a molecular weight of 1800-2000, an equivalentweight of about 900, and a hydroxyl number of about 63 (commerciallyavailable from Rohm & Haas, under the trade designation Paraplex U-148)Moderately branched OH-terminated polyester, formed by reacting adipicacid, hexane triol, and butylene glycol, commercially available fromMobay Chemical Co. under the trade designation Multron R-12 Finelydivided silica viscosity-builder, commercially available from Godfrey L.Cabot, Inc., under the trade designation Cab-O-Sil M-5 75% solids ethylacetate solution of the reaction product of 1 mol of trimethylolpropaneand 3 mols of toluene diisocyanate, commercially available from MobayChemical Co. under the trade designation Mondur CB-75 Talc, 46-micron,maximum Knoop hardness about 12 Ethylene glycol monoethylether acetate,sufiicient to lower viscosity to 2600, cps., viz

The fibrous web described in the preceding paragraph was then passedbetween a pair of 8-inch diameter knurled rubber rolls set with negativeclearance, the lower roll rotating in a pan of the liquid (2600 cps.)composition just described, approximately 177 dry grains per 24 squareinches being applied. The coated web was heated for about 15 minutes at320 F. toreact the isocyanate adduct with the polyester and form anelastomeric polyurethane, the final thickness of the web being about 1%inches. (When the talc was omitted and the composition formed into apatty and cured in the same manner, the tensile strength of the curedcomposition was found to be 5,360 psi. at an ultimate elongation of 35%,the Knoop hardness being less than 1.) Tensile strength of the web wasfound to be 78 lbs. per inch of width in the lengthwise direction and 62lbs. per inch of width in the cross direction.

A 17-inch diameter pad was diecut from the cured bonded web and testedin comparison with a conventional lambs wool pad in the buffing of astandard buifable floor wax. It was found that the appearance of thebuffed wax was similar in each case. The amount of drag exhibited by theproduct of this example was, however, significantly less than that ofthe lambs wool pad, the amperage increase over no-load beingrespectively 0.2 and 0.8 for level and heeled positions. Further, whenthe pad eventually picked up enough wax to detract from itseifectiveness, it could be washed and cleaned easily. In contrast, thelambs wool pad was extremely'difiicult to clean, and exposure to watertended to make it mat even worse than it had before.

EXAMPLE 2 A nonwoven lofty web was formed from 6-denier (approximately25-micron) l /z-inch crimped oriented polyethylene terephthalate fibersin the manner described in Example 1. The web was approximately 1%inches thick and weighed 41 grains per 24 square inches.

A soft mineral-filled binder composition was formed by blending thefollowing components:

I Parts by weight Ethylene glycol monoethyl ether acetate 8 Saturatedpolyester, having an OH number of 47, commercially available from MobayChemical Co.

under the trade designation Multron R-68 15 1,2,6 hexane triol 0.8Mondur CB-75, as in Example 1 13.1 Xylol 8 Talc, as in Example 1 25.5Cab-O-Sil M-S, as in Example 1 0.5

The web described in the preceding paragraph was bonded with theforegoing binder composition in the manner described in Example 1, atotal of 99 dry grains per 24 square inches being applied. The binderwas cured in the manner described in Example 1, the final thicknessbeing /2 inch.

Pads diecut from the bonded web of this example proved outstanding incleaning polymethylmethacrylate (Plexiglas) airplane windows effectivelywithout scratching using conventional cleaning and buffing agents. Usedsimilarly, these pads also cleaned up oxidized and discolored aluminumaircraft bodies. Conventional rubbing compounds could also be used withthese pads to rub down automobile lacquer finishes, and the pad itselfwas extraordinarily efiective in bringing up a high luster withoutimparting the swirl marks characteristic of finishes made using lambswool pads.

EXAMPLE 3 Example 1 was repeated substituting calcium carbonate (Knoophardness of about 135) for the tale. The pad felt both harsher andstiffer than the pad of Example 1, but performance was comparable.

EXAMPLE 4 Example 1 was repeated, increasing the amount of talc so thatit constituted 65% of the total binder volume. The product was extremelyeffective in bufling and showed a lower drag than any of the productsdescribed above. The tensile strength, however, was somewhat lower thanis considered desirable.

When the amount of tale is reduced to of the total binder volume, thetendency to drag increases beyond that which is considered desirable,and ability to impart satisfactory gloss to a bufiable wax is decreased.

EXAMPLE 5 Example 1 was repeated, replacing the talc with kaolin clay(Knoop hardness about 60) in which 12-18% of the particles had anaverage diameter above 5 microns and 62-68% had a diameter of less than2 micron. The product felt similar to that of Example 3, and performanceresults were comparable.

EXAMPLE 6 Example 1 was repeated, substituting -denier nylon for the15-denier polyethylene terephthalate fibers. The cured bonded web wasless lofty than that of Example 1, and pads die-cut therefrom felt harshand were somewhat stiffer.

EXAMPLE 7 Example 1 was repeated, replacing the polyurethane resin inthe binder with a comparable amount of -a 44.5% aqueous emulsion of athermosetting self-crosslinking hard acrylate polymer (Rhoplex HA-24,commercially available from Rohm and Haas); a patty formed from thispolymer has a Knoop hardness of about 1.3 after 6 cure. The pad wassuitable for bufling but lacked the durability of pads made inaccordance with Example 1.

Numerous modifications can be made of the invention describedhereinabove without departing from the spirit of the foregoingdisclosure. For example, the strength of a nonwoven web can be increasedby needle tacking prior to bonding thereby compacting the web andreducing both the openness and percentage void space of the finalproduct. Similarly, different treatments can be applied to the web, forexample to achieve a product having a function for both bufling with acleaning compound and imparting a final luster. To enhance the amount ofcleaning compound which one face of the pad can hold, it is likewisepossible to adhere flock fibers thereto. To increase the hydrophilicnature of a pad which is to be used with aqueous emulsions of polishingcompounds, it is likewise contemplated to treat one face with modifiedpolyvinyl alcohol.

What is claimed is:

1. A soft, resilient, compressible buifing pad which is capable ofimparting a high luster to surfaces of aluminum, paint, wax, plastic andthe like and of cleaning polymethylmethacrylate sheets, all at low dragand without scratching the surface, removing significant amounts ofsubstrate or leaving swirl marks therein, said pad comprising incombination:

a lofty, nonwoven mat having an extremely high void volume andconsisting essentially of crimped tough, strong, synthetic organicresilient fibers having a diameter on the order of 10-50 microns,

said fibers being bonded together at points where they cross and contacteach other with a filled binder which comprises:

a flexible polyurethane resin having a Knoop hardness of no more thanabout 3, and

based on the total volume of binder, about 10% to of a finely dividedmineral filler having a Knoop hardness of no more than about 150.

2. The pad of claim 1 wherein the synthetic fibers consist essentiallyof oriented polyethylene terephthalate.

3. The pad of claim 2 wherein the mineral is present in an amountconstituting about /3 of the volume of said binder.

4. The pad of claim 3 wherein the filler is talc.

5. The product of claim 1 wherein one surface of the pad is providedwith means to enhance its receptivity to aqueous emulsions of buflingcompounds.

References Cited UNITED STATES PATENTS 2,958,593 11/ 1960 Hoover et al.51295 3,026,190 3/ 1962 McMahon et a1. 51-295 3,075,222 1/ 1963 Miller15230.12 XR 3,171,151 3/1965 Sickle et al. 15-118 3,175,331 3/1965 Klein51-402 XR 3,232,729 2/ 1966 Holland 51-298 3,431,689 3/1969 Schnabel51400 DANIEL BLUM, Primary Examiner US. Cl. X.R. 51295, 296

